Designed by medical professionals, our new and improved high tech FXC compression socks feature softer, special Micro-Nylon, making them very easy to put on while delivering true graduated compression with all its benefits: Increased oxygen delivery to the working muscles to enhance their performance. Circulation improvements to help the body eliminate metabolic waste products like lactic acid more easily.The combination of these effects allows you to work longer and harder, delaying the onset of fatigue. The SLS3 FXC compression socks offer more targeted, significant support to the achilles tendons, tibias, calves and ankles, boosting the ability to reduce common ankle and foot injuries. They are recommended for running, cycling, walking, triathlon, skiing, traveling and lots of other uses. The supportive effect and compression of SLS3 FXC compression socks reduce muscle vibration drastically, resulting in less soft tissue damage and less sore muscles. Your recovery time will be significantly reduced. Sizing Calf/Shoe: XS/S: 11.5-13.5"-W6-8; S/M: 12.5-15"-M7-9/W8-10; M/L: 13.5-16.5"-M9-11/W10-12; L/XL: 15-18"-M11-13.